Mon, May 12, 2014 - Page 8 News List

Extent of nuclear cancers unknown

By Ho Jung-chun 何容君

On the afternoon of April 26, the 28th anniversary of the Chernobyl nuclear disaster, I attended a screening of the documentary A2-B-C, at the invitation of the Taipei Bar Association, an invitation which included sitting on the panel for the ensuing discussion. The film, by Ian Ash, a US independent documentary filmmaker who has lived in Japan for 10 years, is a balanced account of the health impact on children exposed to radiation following the March 11, 2011, Fukushima Dai-ichi nuclear disaster.

The film reveals that an increasing number of children are being diagnosed with thyroid cysts and explores subtle changes in their biological and mental health, implicitly challenging the Japanese government’s insistence that radiation remains at safe levels.

This brought back memories of a visit I made, along with some professors, to a community that had been exposed to radiation contamination 20 years ago when I was still at university. I remember doctors examining children there for thyroid cysts, while worried mothers questioned the doctors on the possible health effects to their children and what they could do about it.

The most direct damage of a nuclear disaster is the impact on health due to exposure from radiation. According to a recent official Japanese government report, only a very limited number of individuals were affected by the radiation from the Fukushima Dai-ichi plant. In fact, of the cancers known to be linked to exposure to radiation, leukemia has the shortest incubation period — it can develop in only two years — while the majority of the other types, including thyroid cancer, need anywhere between five and 10 years, or more, to manifest.

Research on the effects of the Chernobyl disaster has shown that the incidents of thyroid cancer in children and adults under 18 years old when initially exposed to radiation from the disaster was 10 to 12 times higher 10 years after the event, than it was five years after.

These results show the importance of long-term monitoring of the health of people exposed to radiation. Notably, however, with this nuclear disaster, the committee of the prefectural government’s Fukushima Health Survey announced on Feb 7, almost three years after the original disaster, that a total of 33 children had already been clinically confirmed to have developed thyroid cancer, an increase of seven from the 26 confirmed cases known in November last year.

These results correspond to the prevalence of thyroid cancer from official reports from the Chernobyl disaster approximately three years after that event.

Today, only two or three years after the Japanese disaster, it is impossible to discount the relationship between the cases of thyroid cancer in children and radiation exposure: Whether the onset of cancer is related to radiation and the relationship between the cancer and the dosage received, whether age is a factor in the incubation period for children, or to what degree this period differs from that in adults, requires more scientific research.

Further, according to a WHO report on the disaster published last year, entitled Health risk assessment from the nuclear accident after the 2011 Great East Japan Earthquake and Tsunami, in the worst affected areas — including Namie-machi town and Iitate-mura village — the preliminary estimated radiation effective doses for the first year ranged from 12 to 25 millisievert (mSv), and the lifetime risk of developing thyroid cancer, breast cancer and all solid cancers is predicted to increase by up to about 70 percent, 6 percent and 4 percent respectively, over baseline rates in females exposed as infants and, for leukemia, by up to about 7 percent over baseline rates in males exposed as infants.

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